"going for two" plays off the use of the football phrase: ie going for the more risky two point conversion, instead of settling for the extra point.

:Encompasses a situation of sexual innuendo, in which it is believed that two people have been alone in private for so long that, not only are they committing some sort of sexual act, but have decided to press their luck and attempt to undertake 2 of such acts within the limited time they had together, before they eventually are interrupted or forced to return.

-Megan and Chris have been gone for way too long... they must be going for two
- Is it safe to go back to the room yet, or do you think they're going for two?